Light emission from single carbon nanotube p-n diodes using electrostatic doping has been demonstrated. See, for example, T. Mueller et. al, “Efficient narrow-band light emission from a single carbon nanotube p-n diode,” Nature nanotech, 5, pgs. 27-31 (2009) (hereinafter “Mueller”). Thus, light emitting diodes (LED) based on carbon materials can be the key building block for future nanometer-scale light sources.
The device structure described in Mueller is top-gated and employs an aluminum oxide gate dielectric. There are however some notable drawbacks associated with this type of structure. First, the use of a top-gated structure reduces the overall efficiency of the device since the gates will cover, and thus block, light emission from the device. Second, the quality of the dielectrics employed is poor due to the difficulties associated with forming high-quality gate dielectrics on carbon materials. Specifically, the carbon materials provide an inert surface onto which the gate dielectrics are to be deposited. Deposition of a high quality gate dielectric, such as a high-k dielectric, on an inert surface is very difficult. Either some seed layer needs to be first coated on the carbon material to promote further high-k dielectric deposition, or a very thick dielectric has to be used. These methods however lead to either severe mobility degradation or non-scalable dielectric thickness. Thus, the result is a non-ideal electrostatic.
Therefore, a carbon material (i.e., carbon nanotube)-based LED device structure that does not suffer from the above-described drawbacks and techniques for the fabrication thereof, would be desirable.